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34
Sound Intensity Calibrator Type 4297 – User Manual
The correction to the indicated sound intensity level is:
L
L
(real)
– (measured)
I
I
where:
T
: ambient temperature, °C
a
P
: ambient pressure, hPa
a
For air, the deviation from the correct reading due to deviating temperatures and pressure is
given in Fig.A.3.
Fig.A.3
Deviation from correct
intensity reading, due
to a present gas
density value of
3
1.205 kg/m
corresponding to the
correct density of air at
1013 hPa and 20 °C
T
273
1013
(
)
×
+
a
10
log
--------------------------------------------- -
=
P
293
×
a
1.0
0dB
-1.0
-2.0
600
700
Atmospheric pressure (hPa)
dB
800
900
1000
1100
881361
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